Consolidated Statement of Equities and Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	$ 7,866,250	$ 7,669,411	$ 6,466,844
Reversal of prior year patronage and redemption estimates	170,147	357,427	394,974
Distribution of patronage refunds	(103,879)	(251,740)	(271,226)
Redemptions of equities	(37,390)	(23,911)	(128,907)
Equities issued	(3,194)	(23,258)	(989,728)
Preferred stock dividends	(139,759)	(164,207)	(145,723)
Other, net	1,983	(291)	(1,735)
Comprehensive income
Net income	127,223	423,969	780,333
Net income attributable to CHS Inc.	127,857	424,192	781,045
Net Income (Loss) Attributable to Noncontrolling Interest	(634)	(223)	(712)
Other Comprehensive Income (Loss), Net of Tax	28,056	2,481	(57,450)
Patronage Refunds, Estimated		(111,587)	(250,177)
Equity redemptions, estimate	(10,000)	(58,560)	(107,250)
Balances	7,905,825	7,866,250	7,669,411
Capital Equity Certificates
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	3,932,513	3,793,897	3,508,473
Reversal of prior year patronage and redemption estimates	(108,821)	(268,017)	(267,088)
Distribution of patronage refunds	153,589	375,506	402,560
Redemptions of equities	(35,041)	(22,948)	(127,707)
Equities issued	(3,194)	(23,258)	(12,365)
Capital Equity Certificates Exchanged for Preferred Stock	19,985	76,756
Preferred stock dividends
Other, net	(9,023)	(1,248)	(2,723)
Comprehensive income
Net income
Other Comprehensive Income (Loss), Net of Tax
Patronage Refunds, Estimated		167,381	375,267
Equity redemptions, estimate	(10,000)	(58,560)	(107,250)
Balances	3,906,426	3,932,513	3,793,897
Nonpatronage Equity Certificates
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	22,894	23,057	23,256
Reversal of prior year patronage and redemption estimates
Distribution of patronage refunds
Redemptions of equities	(389)	(143)	(199)
Equities issued
Capital Equity Certificates Exchanged for Preferred Stock
Preferred stock dividends
Other, net	7,331	(20)
Comprehensive income
Net income
Other Comprehensive Income (Loss), Net of Tax
Patronage Refunds, Estimated
Equity redemptions, estimate
Balances	29,836	22,894	23,057
Non-qualified Equity Certificates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	281,767	282,928	284,699
Reversal of prior year patronage and redemption estimates			(148,579)
Distribution of patronage refunds			147,710
Redemptions of equities	(1,960)	(820)	(1,021)
Equities issued
Capital Equity Certificates Exchanged for Preferred Stock
Preferred stock dividends
Other, net	(753)	(341)	119
Comprehensive income
Net income
Other Comprehensive Income (Loss), Net of Tax
Patronage Refunds, Estimated	126,333
Equity redemptions, estimate
Balances	405,387	281,767	282,928
Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	2,244,132	2,167,540	1,190,177
Reversal of prior year patronage and redemption estimates
Distribution of patronage refunds
Redemptions of equities
Equities issued			(977,363)
Capital Equity Certificates Exchanged for Preferred Stock	(19,960)	(76,756)
Preferred stock dividends
Other, net	(54)	(164)
Comprehensive income
Net income
Other Comprehensive Income (Loss), Net of Tax
Patronage Refunds, Estimated
Equity redemptions, estimate
Balances	2,264,038	2,244,132	2,167,540
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	(211,726)	(214,207)	(156,757)
Reversal of prior year patronage and redemption estimates
Distribution of patronage refunds
Redemptions of equities
Equities issued
Capital Equity Certificates Exchanged for Preferred Stock
Preferred stock dividends
Other, net
Comprehensive income
Net income
Other Comprehensive Income (Loss), Net of Tax	28,056	2,481	(57,450)
Patronage Refunds, Estimated
Equity redemptions, estimate
Balances	(183,670)	(211,726)	(214,207)
Capital Reserves
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	1,582,380	1,604,670	1,598,660
Reversal of prior year patronage and redemption estimates	278,968	625,444	810,641
Distribution of patronage refunds	(257,468)	(627,246)	(821,496)
Redemptions of equities			20
Equities issued
Capital Equity Certificates Exchanged for Preferred Stock	(25)
Preferred stock dividends	(139,759)	(164,207)	(145,723)
Other, net	5,547	(1,505)	6,967
Comprehensive income
Net income attributable to CHS Inc.	127,857	424,192	781,045
Other Comprehensive Income (Loss), Net of Tax
Patronage Refunds, Estimated	(126,333)	(278,968)	(625,444)
Equity redemptions, estimate
Balances	1,471,217	1,582,380	1,604,670
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balances	14,290	11,526	18,336
Reversal of prior year patronage and redemption estimates
Distribution of patronage refunds
Redemptions of equities
Equities issued
Capital Equity Certificates Exchanged for Preferred Stock
Preferred stock dividends
Other, net	(1,065)	2,987	(6,098)
Comprehensive income
Net Income (Loss) Attributable to Noncontrolling Interest	(634)	(223)	(712)
Other Comprehensive Income (Loss), Net of Tax
Patronage Refunds, Estimated
Equity redemptions, estimate
Balances	$ 12,591	$ 14,290	$ 11,526